Question

help pls

Answer 1

\[\sum_{n=3}^{8}5n=15+20+25+30+35+40=?\]

Answer 2

you just need to add up the above numbers

Answer 3

use ur calculator

Answer 4

what about the last one? @welshfella

Answer 5

\[\sum_{n=1}^{ \infty }-4\left( \frac{ 1 }{ 3 } \right)^{n-1}\]
a. put n=1,2,3,4
b.& C.\[S=\frac{ -4 }{ 1-\frac{ 1 }{ 3 } }=-4 \times \frac{ 3 }{ 2 }=-6\]
which is finite
so it converges.